hello, i bought this oven and I'm using a 30mbar regulator since I'm using a mixture of butane and propane and i have the greek type of injector. my problem is that the stone takes a long time to heat up and the flames, although blue and hot, are very short even at full blast. is it possible i need a 37mbar regulator even though I'm using a mixture of has? every gas oven i see has big rolling flames and mine has very short, 3cm tall flames. is this normal?